The present disclosure relates generally to fuel pumps, and is more particularly concerned with a new and improved single plunger fuel pump.
In a typical high pressure, reciprocating plunger fuel supply pump, the plunger reciprocates within a surrounding sleeve which is secured in the plunger bore hole. The sleeve bears on a shoulder or other mounting surface in the housing. To achieve ideal performance and long life, the plunger OD and the sleeve ID must be precisely sized with close tolerances and installed in a manner that preserves a precise fit.
Notwithstanding the precision with which the sleeve and plunger may be fabricated, the installation in the pump housing can produce slight misalignment of the plunger within the sleeve. This misalignment can cause excessive or non-uniform wear on the plunger, and can also affect the fluid seal between the sleeve and the housing, giving rise to excessive leakage. Such misalignment is due to an imbalance or asymmetry in the axial force applied around on the sleeve to bear against the mounting surface of the housing.